This invention relates generally to a vehicle safety apparatus, and more particularly to an alertness monitor for sensing vehicle operator fatigue and providing an appropriate warning signal to such operator.
The motor vehicle, while being one of man's greatest modern technilogical advances, also represents one of man's significant instruments of death, injury, and property damage. However, most motor vehicle accidents can be traced directly to operator error rather than through any fault of the vehicle itself. A primary cause of such operator related vehicle accidents is operator fatigue. Fatigue decreases the alertness of the operator such that proper attention is not paid to operation of the vehicle. Fatigue can result from vehicle operation over extended periods of time or under monotonous operating conditions. Moreover, the opertor's physiological condition with regard to the influence of alcohol, drugs or mere mental preoccupation has a direct bearing on fatigue. When an operator is fatigued, his control over the vehicle is impaired and may become erratic to the point where an accident is possible.
Many proposals have been made for preventing hazardous vehicle operation due to lack of operator alertness resulting, for example, from fatigue. For example, dexterity tests may be coupled to the ignition system for the vehicle so that if such tests are not successfully completed by the operator, the vehicle cannot be started. However, such dexterity tests are not applicable to conditions existent after the vehicle is in operation. Other proposals include requiring the operator to respond to external stimuli in order to check his degree of alertness or examining the operator's physical condition by, for example, measuring operator eyeball movement or steering wheel oscillations. However, such proposals are comparatively slow in detecting a decrease in alertness and, further, are often erroneous due to the various conditions over which the vehicle is operated. Moreover, physical motion sensing mechanisms are cumbersome and interfere with normal operator control of the vehicle.